Preparation and thermoelectric properties of AgPb18SbTe20−xSex (x = 1, 2, 4) materials

AgPb₁₈SbTe_20−xSe_x (x = 1, 2, 4) bulk materials were prepared by combining hydrothermal synthesis and melting. Thermoelectric properties were measured from room temperature up to 773K. The materials showed n-type conduction and exhibited degenerate semiconductor behavior. The power factors of the materials varied greatly with increase of Se content (x). Partial substitution of Se for Te in AgPb₁₈SbTe₂₀ resulted in remarkable reduction of thermal conductivity in the whole temperature range and increase of power factor at lower temperatures; therefore, the dimensionless figure of merit, ZT, was enhanced below 600K. A maximum ZT value of ∼0.82 is obtained at 523K for the AgPb₁₈SbTe₁₈Se₂ sample.